A recent radio communication environment faces a problem of rapid increase of data traffic. Therefore, in 3GPP, as disclosed in the following Non-Patent Literature 1, it is studied to disperse traffic by increasing network density by providing a plurality of small cells within a macro cell. Such a technique which utilizes small cells is referred to as small cell enhancement. Also in proposal of the fifth generation wireless communication scheme, as disclosed in the following Non-Patent Literature 2, introduction of an ultra-dense network using higher and wider band than that of an existing network is forecasted.
A small cell is concept which can include various kinds of cells (such as, for example, a femtocell, a nano cell, a pico cell and a micro cell) which are disposed while overlapping with a macro cell and which are smaller than the macro cell. In one example, the small cell is operated by a dedicated base station. In another example, the small cell is operated by a terminal which becomes a master device temporarily operating as a small cell base station. A so-called relay node can be also regarded as one form of the small cell base station. In an environment where such small cells are operated, it is important to efficiently utilize radio resources and provide a low-cost device.
The small cell base station typically relays traffic between a macro cell base station and a terminal. A link between the small cell base station and the macro cell base station is referred to as a backhaul link. Further, a link between the small cell base station and the terminal is referred to as an access link. When the backhaul link is a radio link, by operating the radio backhaul link and the access link using a time division system, it is possible to avoid radio signals of these links from interfering with each other.